Let-off for looms



y 1956 M. R. FLAMAND 2,745,439

LET-OFF FOR LOOMS Filed June 11, 1952 2 Sheets-Sheet 1 INVENTOR. MAURICE R. FLAMAND A TTORNE Y May 15, 1956 M. R. FLAMAND 2,745,439

LET-OFF FOR LOOMS Filed June 11, 1952 2 Sheets-Sheet 2 mum I manna JNVENTOR. MAUEIcE I2. FLAMAND A TTORNE Y United States Patent LET-OFF FOR LooMs Maurice R. Flamand, Central Falls, R. 1., assignor to Draper Corporation, Hopedale, Mass., a corporation of Maine Application June 11, 1952, Serial No. 292,898

7 Claims. (Cl. 139-110) This invention pertains to improvements in let-off means for looms, and more specifically, to improvements in that part of such means which governs the positive and periodic ratcheting movement imparted to the letoff through gearing interconnected to a warp beam.

It is a general object of the invention to improve that part of let-off means for looms which involves the periodic ratcheting of the gearing interconnected to the beam and so to devise that ratcheting means that it shall function to advance the beam through extremely small increments of movement.

It is a more specific object of the invention to devise ratcheting means for such let-01f motions that shall not depend upon a pawl motion of relatively great angular extent as has heretofore been required, but to devise a ratcheting means such that practically continuous movement of the parts throughout a very small angular extent shall be possible, and therefore make unnecessary greater periodic movements interspersed with relatively long periods of rest of the warp mechanism as has heretofore frequently been required.

It is a more specific object of the invention to devise ratcheting means of the type described which shall be relatively silent in its operation and which shall involve very little wearing of parts even though the actual surfaces between the so-called ratchet wheel and its advancing pawl are only minutely roughened or serrated thereby requiring very small return movements for the engagement of a new portion of the ratchet wheel by the advancing pawl.

it is a further object of the invention to devise ratcheting means for the purpose described which shall, in apparent efiect, function practically continuously upon the let-off mechanism and on the beam governed thereby rather than with varying intermittent impulses as has heretofore been the case.

Further objects of the invention will be apparent from the following more detailed description.

According to previous practice, warp beams mounted on weaving looms have been rotated'to release the warp threadsbeing drawn under tension whenever tension has exceeded a predetermined amount. The control for such function has been governedby certain movable elements afiected by the tension of the threads themselves which in turn control the amplitude of movement of other periodically and continuously actuated parts functioning to impart a motion to a beam driving gear train through a ratchet wheel and pawl or pawls. One form of such mechanism commonly employed includes a gear train in which are to be found a worm wheel and Worm for driving the same, said worm being mounted on a shaft on which a brake drum is also fixed. Brake shoes are applied to the drum in a known manner so that normally the said brake prevents rotation of the worm even though the warp threads are drawn under considerable tension, except as the let-ofl. or beam advancing means comprising a ratchet wheel and ratchetmg distance the arm is actually moved. Since there is no I selves.

2,745,439 Patented May 15, 1956 ice or other mechanism which is in turn positioned'in ac-,

cordance with the tension in the warp threads themamounts to a relatively great advancing movement interspersed between periods of dwell for the beam and other parts since, due to the fact the ratchet wheel teeth are relatively long, there may be one or more idle movements of the pawl each of longer extent, but still less than the distance between the teeth, before it actually grips the next tooth thereby to move the beam throughout a definite angular extent to let off warp. As a result of this the control shifts back and forth between positions where it permits very little or no motion at all for the parts to that where a maximum and effective movement is imparted to the beam, whereupon the cycle then starts.

again so that the next movement is very small, or at least something far less than the movement required for advancing the ratchet wheel for a complete tooth. Of course, the direct result insofar as the weaving function is concerned is that the tension mustincrease appreciably in order to cause the letting off of warp threads whereupon the more extended let-off movement then causes an undesired relaxing of the tension beyond what would theoretically be considered better practice.

Again, the fact that the ratchet wheel teeth and the pawl operable therewith have been of appreciable size has necessitated the use of fairly heavy spring means to keep the pawl in engagement with the teeth so that considerable noise has been experienced, especially when operating at higher speeds.

According to the invention which will hereinafter be described in greater detail, a ratcheting means has been devised which may be moved throughout very small angular extents and will actually advance the gear train through the ratchet wheel for very minute angular distances, these angular movements being something far less than the movement incidental to the ratcheting of a single tooth on the ratchet and pawl mechanisms heretofore used. A ratchet wheel is connected through to a more or less conventional gear train and that ratchet wheel is caused to move throughout small angular in crements since, instead of employing the usual ratchet teeth such as have been well known and used for many years, the surface or periphery of the wheel which is engaged by the pawl means is merely roughened, that is, may be serrated or knurled, it not actually being necessary to out well defined teeth in the wheel so long as it is of sufiiciently rough nature so that the pawl functioning therewith may grip it effectively without applying too great pressure between the engaging surfaces.

The pawl is pivoted and spring pressed, but its wheel engaging surface is one which is knurled, serrated or roughened in the same manner as the periphery of the wheel and is so operated that upon return movements, that is, movements to pick up or engage the wheel at a new position, the actual engagingparts of the elements are separated more or less radially of the wheel. Thus there is no slipping or sliding of the pawl member over the roughened surface of the wheel. Then on the active or wheel advancing movement, a spring is employed for pressing the pawl against the wheel and the ratcheting movement imparted through an arm on which the pawl' is pivoted must advance the wheel for whatever angular In these devices the actual operation generally sliding of the parts over one another, there is very little wear and the fa'c't'th'a't' the roughened surfaces, serrations, etc., do not wear and thus may be of relatively fine nature, makes it possible for the ratchet means to function upon angular movements of much smaller extent, for example, for not more than one-tenth of the actual movern'ent which would be required for engagement of a tooth in the conventional mechanism. If necessary, the novel means may advance the wheel asrapidly as is desired since of course, the control may be such that the arm carrying the pawl moves for a relatively greater extent. That is the case when fabric is being woven in which must be released at a rapid rate.

' owever, for any and all fabrics, the motion is one which is virtually continuous in that the ratcheting at each movement of the lay or other control means from which the ratcheting of the let-ofi is taken will advance the beam throughout the same extent thereby obviating the periodic dwells which haveheretofore been interspersed with the relatively long beam advancing movements. V 7

There are two forms herein'illustrated which the invention may take and in the following paragraphs the details of these forms will be specifically described. The invention is not limited to the mechanism precisely as shown here and this disclosure is to be considered as V merely illustrative of two specific mechanisms which may be employed advantageously.

In the figures of drawing:

Fig. 1 is a side elevation showing part of the loom to which the invention has been applied and the relationship thereof with other parts incidental to the let-off function.

Fig. 2 is a section taken through part of the let-off Fig. 5 is a side elevation of the parts illustrated in- Figs. 3 and 4.

Figs. 6, 7 and 8 are corresponding views showing a second form which the invention may take.

Now referring to Figs. l and 2, the let-elf means is applicable to typical looms having a loomside 1t), warp beam 11 mounted on the usual bearings indicated by num'e'ral 12 adjacent the back of the loom, said warp beam having a ring gear teeth of which are shown at 13 and which are normally in mesh with teeth of a pinion 14 after the beam has been properly mounted. Pinion 14 is fixed at the inner end of a shaft 15 rotated by a gear train presently to be described. The shaft 15 is carried in bearings or bushings mounted in brackets 16 and 17, these being bolted at opposite sides of the loomside and serving as a rigid mounting means for shaft and other parts.

The shaft 15 has keyed at its outer end a worm wheel 18 along with a hand wheel 19 by means of which the pathway for the beam is' cleared so it may be mounted or removed without interference. As abeam is to be removed or while mounting abeam in the loom, the shaft 15 with the pinion 14 is slid outwardly by p'ulling on hand wheel 19 after loosening collar 20 thereby providing suitable clearance for the parts. This is merely incidental part of the mechanism shown and has no direct bearing on the invention.

The outer bracket 17 is provided with a forked portion at the extreme ends of eachbranch of which is found-a bearing member 21 or :22. These support 'a vertically disposed shaft or spindle 23, rotatable in said bearing members and carrying-amworm 24 whichis in operative engagement with the worm wheel. 18. The

there are relatively few picks per inch so that the warp 7 worm wheel 18 permits the shaft 15 to slide therein but the two rotate synchronously since they are provided with a suitable key. Shaft 15 may be moved outwardly or inwardly as heretofore mentioned, but is rotated by the worm and wheel drive.

The vertical shaft or spindle 23 also carries above the bearing member 22 a brake drum 25 engaged by brake shoes capable of being manually released in a known manner and generally indicated by numeral 26, these parts not being described in greater detail here since they'are well known and adescription and further illustration thereof is evident in U. S. Patent 2,273,474.

At the upper end ofthe spindle between a hand wheel 27 and the brake mechanism, is positioned the ratcheting means which functions to'rotate the worm 24 thereby advancing the warp beam itself through worm wheel 18, shaft 15, pinion 14 and gear 13. This ratcheting means is hereinafter to be described in greater detail by reference to Figs. 3, 4' and 5, and, among other parts, includes an operating arm 28 by means of which the'pe- 'riodic ratcheting movements are imparted. For that purpose, a camindicated by numeral 29 and carriedon a shaft 30 which may preferably be the cam shaft of the loom is engageable with a follower 31 positioned on an extension 32 projecting laterally and forwardly from the lowermost arm 33 of a two-armed lever pivoted at 34, the upper arm 35 of which is interconnected by alink 36' to an arm 37 movable with the whip roll 38, this latter mechanism being of any well known type such as may commonly be employed for the purpose. The roll and arm are moved in accordance with the tension in the warp sheet so that as the tension in the warp increases, the parts are positioned to swing the arm 35 of the two-armed lever forwardly or clockwise as viewed in Fig. 1, thereby moving the extension 32, arm 33 and follower 31 to a position where the eccentricity of cam ratcheting means so that according to the effect of the warp sheet as conveyed through the whip roll 38 and.

mechanism just above described, a greater or a lesser oscillatory movement of arm 28 is to be expected.

Now referring to Figs. 3, 4 and 5, mechanism incidental to one formof the invention will be specifically described. The shaft 23 has what will be called a ratch et' wheel fixed thereto by suitable set screws or other means, this wheel being indicated by numeral 40. The: term ratchet wheel is employed to denote the general 7 character of the member, although it differs. markedly from what is generally thought of I as a ratchet wheel. The periphery of the wheel is roughened in any convenient' a'nd satisfactory manner. One method involves cutting or forming the serrations 41, although it is to be understood that'the periphery of the wheel may be.

knurled, or satisfactorily roughened in any other manner. The depth of theteeth or depressions need not be great, an'd'i'nfact', ne'ed'not be even either as to depth or spacing-sodon'gas the" entire periphery is roughened leavingno blank spaces of appreciable extent. Since the wheel is fixed totlieshaft2 3, it is adapted to turn that shaft and the worm 24 as it is advanced during loom operation. The serratio'nsxor the like need not facein one. direction as do'the usual ratchet wheel teethh A yoke Y has an upper arm 42 and a lower arm 43 and is" freely" rotatable upon the'shaft 23 being maintained invertical position by its engagement upon-the top'surface of the brake drum 25 or by engagement upon some other vertically fixed part. A pivot 44 an acent the" outer or free end of the yoke connects the latter ze-'arm 2s;1 revious1y mentioned, and also mounts" a pawl member 45 having adjacent the wheel 40 serrations, knurling, or other roughened surface structure, op erably compatible with that at 41 on the ratchet wheel.

The pawl member 45 has these serrations or its roughened portion 46 preferably formed on an arc the center of which is eccentric to the pivot 44 and so offset to the pivot that movement of the pawl in the direction indicated in Fig. 4 moves the wheel engaging portion 46 quickly away from the ratchet wheel and in a direction approximately radially of the wheel so that there is no rubbing or frictional contact between the surfaces on this return or resetting movement preparatory to reengagement of the wheel after one advancing movement thereof. The arm 28 is provided with a pin 46 extending vertically downward for engagement within an enlarged opening 47 in the member 45. A spring 48 is fixed at the outer part of the yoke at screw 49 and tends to push the pawl member into engagement with the wheel when such engagement is permitted by the position of the arm 28.

Having now described the parts entering into the combination illustrated in these Figs. 3, 4 and 5, reference to Fig. 3 shows that movement of link 39 in the direction of the arrow affects arm 28 which is at that time in contact with the hub 50 of the ratchet wheel 40 and with that contact point as a fulcrum swings the arm and yoke in the direction of the arrow at the right hand portion of Fig. 3. Obviously, the arm, yoke, pawl member and wheel are moved as a unit about shaft 23 as a center thereby rotating the wheel 40 throughout an angular extent depending upon the movement of the arm 28.

Now continuing with Fig. 4, the link is then moved reversely or in the direction of the arrow of the figure, first moving the pawl member 45 about pivot 44 and against the tension of spring 48 until the teeth 46 clear the teeth 41 of the wheel and also until that part of the pawl member indicated by numeral 51 engages with the adjustable stop screw 49 which, as before stated, also serves to maintain the spring 48 in position. A lock nut 52 serves the purpose of holding the spring and also of maintaining the setting or adjustment of the screw. When the member 45 stops against the screw 49, further movement of lever 28 then swings the yoke as indicated in the figure throughout a slight angular extent and as the link 39 is again moved as in Fig. 3, the member 45 will engage the wheel 40, but the roughened or serrated portions thereof will have made contact and will effect an active engagement at a point somewhat advanced from that previously effected, the amount of advance or the new grip obtained at this time being dependent upon the extent of oscillation of the link 39. Depending upon the movement or" the tension controlled members, this may be a very slight angular movement, or may be as great as is needed under the circumstances. However, for continuous and uniform loom operation, the extent of movement incidental to its resetting of the pawl member and periodic advance of the wheel 40 always approach very closely to the same value.

Since the roughened portion 46 of the pawl member 45 is formed on an arc eccentric to the pivot center 44, and since the eccentricity is offset in the direction indicated, upon movement of the arm 28 as indicated in Fig. 3 there is a toggle action which, in addition to the pressure exerted by spring 48, presses the roughened surfaces 41 and 46 together so that there can be no slipping. The roughened surface 46 is preferably formed on an arc, but may be relatively straight, in that event, the are merely having an infinite radius.

Now referring to Figs. 6, 7 and 8, a modification is shown in which the number and also the complication of parts is reduced. The shaft 23 in this instance mounts a wheel 53 corresponding to the ratchet wheel 40 and having a roughened periphery similar to that previously described. A yoke or single arm such as is here shown at 54'is freely pivoted at the shaft 23 and has an offset or angularly bent end 55 adjacent which is pivoted as at 56, a pawl member 57 having a. roughened wheel engaging surface 58 which is pressed into position by a spring 59 similar to the spring 48, previously mentioned. The link 39 connects in this instance to a pivot 60 directly connected to or projecting upwardly from the pawl member 57.

Fig. 6 shows the position of the parts and the manner in which the wheel 53 is advanced. In Fig. 7 the parts are shown as the pawl member is being reset preparatory to the next advancing movement. Here the bent end 55 of the arm 54 carries a screw 61 which serves both as a stop screw and in conjunction with a lock nut 62 for holding the spring 59 in place and the pawl member stops against this screw as the resetting movement first swings the pawl member out of engagement or contact with the surface of the wheel whereupon the arm 54 is swung about its pivot after which the return movement of the spring 59, Fig. 6, first engages the pawl member with the wheel and thereafter swings the unit about the center of shaft 23 for the advance let-oif movement eventually imparted to the warp beam itself.

The eccentricity of the arc of the engaging surface 58 as compared to the center 56 corresponds to similar arrangement of the corresponding parts of Figs. 3, 4 and 5 and it is believed that it will be obvious to those skilled in the art that the modified form of the invention may be used to impart either extremely small or greater angular movements as required to the shaft 23 and through worm 24, the worm gear and other elements in the train for advancing the warp beam itself which is otherwise maintained stationary by the action of the brake mechanism 26.

The novel part of the let-off means, while shown as applied to one common type of let-off, may be applied to all such means as utilize a ratchet type of beam advancing mechanism. 7

While one embodiment and a modification of the invention have been disclosed, it is to be understood that the inventive concept may be carried out in a number of ways. The invention is, therefore, not to be limited to the precise details described, but is intended to cover all variations and modifications thereof falling within the spirit of the invention and the scope of the claims.

I claim:

1. In a loom having a warp beam from which a warp sheet is drawn and a whip roll over which said warp sheet is passed, a warp let-off means comprising gearing for advancing said warp beam as governed by tension in said warp sheet and means for positively advancing the gearing which comprises a ratchet wheel and a pawl means for said wheel, an arm pivoted concentrically with said wheel, a pawl means pivoted to said arm for swinging to and from contacting engagement with said wheel, said wheel and pawl means having their contacting surfaces roughened, the contacting surface of the pawl means being eccentrically disposed to its point of pivot, and means connected-to said arm and pawl means and being so disposed that in cooperation with the eccentricity of the contacting surface of the pawl, it effects a toggle action between the pawl means and wheel to develop gripping pressure at their contacting surfaces as it moves the arm, pawl means and wheel in an advancing direction.

2. In a loom having a warp beam from which a warp sheet is drawn and a whip roll over which said warp sheet is passed, a warp let-off means comprising gearing for advancing said warp beam as governed by tension in said warp sheet and means for positively advancing the gearing which comprises a ratchet wheel and a pawl means for said wheel, an arm pivoted concentrically with said wheel, a pivot at the free end of said arm, a pawl means restrictedly movable about said pivot and having a wheel engaging surface formed on an arc the center of which is eccentric to said pivot for the pawl means, and means 7 confieet'e'd to said arm and pawl means amassing so dis= posedthat cooperation with the; eccentricity of the" contacting surface of the pawl, it efiect's a toggle action between the pawl means and wheel redevelo gripping pressure at their contacting surfaces" as it moves the arm, pawl means and wheelinan advancing" direction;

3. In a loofn having a warp" beam from which a warp sheet is drawn and a whip roll over which said warp sheet is passed, a warp" let-off means comprising gearing for advancing said warpbeam as governed by tension in said warp sheet and means for positively advancing the gearing' which comprises a ratchet wheel and a pawl means foe said wheel, an arm concentrically pivoted with respect re said wheel and a pivot means at the relatively free end of said arm about which said pawl means is movable to and from engagement with the surface of saidwheel, said wheel and pawl means having their contasting surfaces roughened, the contacting surface of the pawlm'eans' beinge'ccent'rie'ally disposed to its point of pivot, an arm pivoted at the pivot point of said pawl means, a spring means normally urging said pawl means I into engagement with the wheel and a connection between said last mentioned arm and pawl means such that as the arm is moved in one direction it retracts the pawl from the wheel, but when moved in the other direction it permits the pawl to move into engagement with the wheel and swings the pawl means, arm and the wheel in an advancing movement.

4. In a loom having a warp beam from which a warp sheet is drawn and a whip roll over which said warp sheet is passed, a warp let-ofi means comprising gearing for advancing said warp beam as governed by tension in said warp sheet and means for positively advancing the gearing which comprises a ratchet wheel, an arm pivoted concentricall'y with said wheel, a pivot means at the free end of said arm, pawl means swingable about said pivot means to and from a contacting engagement with the surface of the wheel, said wheel and pawl means having their contacting surfaces roughenedflhe contacting surface of the pawl means being eccentrically disposed to its point; of pivot, a spring means normally urging the pawl means into engagement with the wheel and a stop for limiting its movement in the opposite direction, a second arm pivoted at the pivot point of said pawl means and interconnecting means between said arm and pawl means effective upon the pawl between its pivot and the point 1 at which it engages the ratchet wheel by which the pawl,

when the arm is moved in one direction, is retracted from the wheel and the arm first mentioned is swung about swag-rec I first mentioned and pawl meansthroughout a limited angular" extent.

5. In a loom having a warp beam from which a warp sheet is drawn and a whip roll over which said warp sheet is passed, a warp let-off means comprising gearing for advancing said warp beam as governed by tension in said warp sheet and means for positively advancing the gearing which comprises a ratchet wheel and a pawl means for said wheel, said pawl means comprising an arm pivoted concentrically with said wheel, a pivot at the relatively free end of said armfor said pawl, the engaging surfaces of the wheel'- and pawl being roughened and that of the pawl being formed on. an arc eccentric to the pawl pivot, a spring for urging the pawl into engagement with the wheel, and reciprocatory means for moving said arm and pawi through a small angular extent to ratchet said wheel, said means being connected to' said pawl between its pivot and the point at which it engages the ratchet wheel for withdrawing the pawl from the wheel against the tension of said spring.

6. In a loom having awarp beam from which a warp sheet is drawn and a whip roll over which said warp sheet isp'assed, a warp let-off means comprising gearing for advanc'ing said warp beam as governed by tension in said warp sheet and means for positively advancing the gear ing which comprises a ratchetwheel interconnected to said gearing, an arm pivotedconcentrically with said wheel, a pivot at the free end of said arm and a pawl mounted for swinging movement about said pivot, said' wheel having its periphery formed with serration-like indentations, said pawl having a corresponding wheel e gaging surface formed on an arc eccentric to the pawl pivot, a spring for'urging the pawl into engagement with the wheel, and a reciprocating means connected to said pawl at a point between its pivot and the point at which it engages the ratchet Wheel for moving it against said spring to release it from the wheel and to swing it and the arm reversely to the advancing movement of the the Wheel pivot to reengage the pawl in an advanced position, said arm serving when moved in the opposite direction to permit engagement of the pawl means with the surface of the wheel and to advance the wheel, arm

wheel and then, when moved oppositely, being effective for engaging the pawl with the wheel and for advancing both arm and wheel to let ofl warp.

7. Mechanism as defined in claim 6 vwherein said reciprocating means connected to said pawl comprises a link connected to the said pawl between its pivot and the wheel engaging surface thereof.

References Cited in the file of this patent UNITED STATES PATENTS 257,874 Kosiuski May 16, 1882 871,765 McBrier et al. Nov. 19, 1907 1,383,331 'Nordstrom July 5, 1921 

